(1) Field of the Invention
The present invention relates to a high-density liquid hydrocarbon fuel, and more particularly to a high-density and high energy liquid fuel used for jet propulsion of rockets or jet engines.
(2) Description of the Prior Art
In a rocket or a jet engine for a turbo jet, a ram jet, a pulse jet or the like, a high-energy liquid fuel is used. In order to increase the propulsion force of such a jet engine, a fuel having a greater combustion energy per unit weight, i.e., a high-density and high-combustion heat release liquid fuel, is required. The liquid fuel for jet engines is fed to a combustion chamber through a pipe, but since a flying object carrying the jet engine flies at a high altitude and since liquid oxygen is also used, the liquid fuel will be exposed to an extremely low temperature. Therefore, an additional requirement of the liquid fuel for jet engines is that freezing point and viscosity are low even at low temperatures. Further, it is also necessary that the liquid fuel for rockets and jet engines has no unsaturated bond and can be stored stably for a long period of time.
As such liquid fuels for rockets and jet engines, there have been known exo-tetrahydrodicyclopentadiene (JP-10; Japanese Patent Publication No. 20977/1970) which can be prepared by the isomerization of hydrogenated dicyclopentadiene with an acid catalyst, and a compound which can be prepared by hydrogenating a dimer of norbonadiene (RJ-5; U.S. Pat. No. 3,377,398). The aforesaid JP-10 is good in fluidity at low temperatures but is low in density, which disadvantageously lowers the volumetric heat of combustion. On the other hand, the aforesaid RJ-5 has a large heat of combustion, but its fluidity at low temperatures is too poor. Moreover, the RJ-5 has the drawback that it is difficult to synthesize and is expensive.